1. Field of the Invention
The present invention relates to fiber optics, and more particularly, to image transmission over a bundle of optic fibers.
2. Description of the Related Art
There are many uses for transmitting light through an optic fiber and the number of uses increases each year. Inventors working in the field of fiber optics are generating many new and improved uses for optic fibers in both the decorative and technical arts. From the beginning of the technical development of fiber optics, it has been recognized that a bundle of optic fibers presents an excellent method for magnifying or expanding images. By maintaining the fibers at one end of the bundle or cable in a close relationship to receive a small image and then spreading the fibers at the other end to produce a large image, it is possible to magnify pictures of various kinds. The light entering at the small end must be of sufficient intensity in order to obtain an image at the other end that is capable of being seen. Normally, the intensity required to view a magnified image through a fiber optic taper is similar to the intensity required to see an image through a common magnifying glass.
The most common device using fiber optics to magnify an image is the fiber optic taper. A fiber optic taper is a symmetrical bundle of tapered optic fibers wherein the fibers have been well aligned (coherently aligned), and wherein each of the optic fibers is tapered from a wide end to a narrow end. It is important that the relative position of each fiber be maintained from one end of the bundle to the other, so that light entering a fiber at one end of the taper exits the fiber at the other end of the taper in the same relative position. An image may then be transmitted from one face to the opposite face with either a reduction or magnification in size. For example, when the small end of a fiber optic taper is placed in contact with an object such as a printed page, an enlarged image appears at the upper, larger face of the taper. Specifically, the size of the transmitted image is in direct proportion to the change in size of the two ends of the fiber optic taper. Size ratios, i.e., magnifications, of from nearly unity to as much as 10:1 may be practically obtained using a fiber optic taper. Each fiber in the bundle transmits one xe2x80x9cpixelxe2x80x9d of light from an image at one end of the fiber optic taper to the other end of the taper.
A disadvantage of the fiber optic taper is that it achieves its magnification by the gradual increase in the diameter of each optic fiber in the bundle. Since each fiber in the bundle must increase its diameter proportionally, the overall volume of the fiber in the taper increases exponentially as the magnification factor increases. Thus, optical tapers are short, fat, heavy and provide relatively low magnification. A modest sized optical taper is quite bulky and can have a weight in excess of one pound resulting in high manufacturing costs and limiting the value and application of an optical taper.
As one improvement to the fiber optic taper, Jeskey, in U.S. Pat. No. 4,693,552, describes a fiber optic bundle that may be used for magnification and for transmitting an image that does not use a tapered optic fiber. Instead, Jeskey discloses using a bundle of optic fibers, all having a uniform cross section, with each of the fibers cut at a narrow acute angle at the display end of the bundle, and spreading the fibers apart at the viewing end by separating each of the fibers with a spacer. By cutting the display end off at an acute angle, a display surface is generated having a greater surface area than the cross-sectional area of the optic fiber. The degree of magnification is equal to the ratio of the surface area of the cut display area and the optic fiber""s cross-sectional area. Because the display area is increased by cutting the display end at an acute angle, there is no need to taper the optic fiber from a narrow end to a wide display end as is necessary in the conventional fiber optic taper, providing an advantage of less bulk and less weight.
However, there is still a need for smaller, less bulky fiber optic bundles that may be used for transmitting an image for viewing. There is a need for a lightweight alternative to LED displays and other bulky heavy displays that are currently used as displays on portable computers and other devices having display screens. There is a need for small portable display screens that are not large power consumers so that portable devices having display screens may operate for longer periods of time on their limited battery resource.
The present invention provides an apparatus that may be used to transmit an image from a light source to a viewing end. The apparatus comprises a bundle of optic fibers having a base end with a first angle across the bundle and a viewing end, wherein the viewing end of each optic fiber is cut to expose an interior side face as a viewing area having an aspect ratio of approximately 1:1. Because the aspect ratio of each of the viewing areas is approximately 1:1, it is not necessary to insert spacers between the optic fibers at the viewing end.
While the optic fibers may have any cross sectional shape, preferred shapes are an elliptical or rectangular cross section. Thin optic fibers are preferred with a cross sectional shape having a major axis that is longer than a minor axis. At the viewing end, each of the optic fibers is cut in a shape selected from a notch, an s-curve or a slant cut. Other cuts are possible provided the cut provides a viewing area having an aspect ratio of approximately 1:1. The optic fibers may have a uniform cross section extending from the base end to the viewing end or the optic fibers may have a non-uniform cross section extending from the base end to the viewing end. When the optic fibers have non-uniform cross sections, the cross section may, for example, transition from a round shape or a square shape at the base end to an elliptical shape or a rectangular shape at the viewing end. Preferably, if the cross section of the optic fibers are not uniform, the optic fibers will transition from a shape having approximately a 1:1 aspect ratio at the base end to a different shape at the viewing end.
To provide magnification at the display end, each of the interior side faces has a greater surface area than the cross sectional area of each of the optic fibers.
The optic fibers may be arranged in rows and columns in the bundle. In one embodiment of the invention, the optic fibers may be elliptically shaped and arranged in a lattice within the bundle of optic fibers.
At the base end of the bundle, a light image generator is mounted adjacent to the base end of the bundle. The light image generator may be a cathode ray tube, a plurality of light emitting diodes (LED) or a plurality of lasers. Any light image generator would be acceptable for use with the present invention provided the light from the generator may be directed into the base end of each of the optic fibers.
The relative position of each optic fiber may be maintained from the base end to the viewing end. Alternatively, the relative position of each optic fiber may not be maintained from the base end. The first angle at the base end may be substantially at a right angle to the axis of the optic fiber or alternatively, may be an oblique angle. The viewing end may form either a non-directional field of view or a directional field of view.
Preferably, the optic fibers are bonded together in the bundle with a flexible glue. The flexible glue may be a silicon rubber. Alternatively, the optic fibers may be fused together. If the fibers are bonded with flexible glue, then the bundle will be flexible and able to bend and adjust to a convenient viewing position. If the fibers are fused, the bundle will not be flexible.
The present invention further provides a method of using a bundle of optic fibers comprising receiving light at a base end of each of the optic fibers from a light source and transmitting the light through the optic fibers to a viewing end, wherein each optic fiber is cut at an obtuse angle on the viewing end, and wherein the obtuse angle exposes a face having an aspect ratio of approximately 1:1. The method further comprises forming an image on the viewing end, wherein each optic fiber transmits one pixel of the image to the viewing end, and wherein the light source varies characteristics of the light received at the base end of each of the optic fibers. The image may be formed by varying the characteristics of the light generated by the light source, wherein the characteristics are selected from intensity, color and combinations thereof. The method may be used to provide an image for a television, DVD player, computer, video camera or any other devices that are image generators. Therefore, the characteristics of the light are varied by the image-generating device to form the desired image at the display end of the bundle.
The present invention also provides a method of making a display device comprising, bundling a plurality of optic fibers into a bundle, and cutting a viewing end of the bundle with an obtuse angle across the bundle, wherein the obtuse angle cut exposes a face having an aspect ratio of approximately 1:1. The method further comprises cutting a base end of the bundle with a first angle across the bundle. The optic fibers may be bound with a flexible glue, such as silicone rubber, or the optic fibers may be fused together. Alternatively, the optic fibers may be held together by any means that maintains the viewing end of each optic fiber in position.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of a preferred embodiment of the invention, as illustrated in the accompanying drawing wherein like reference numbers represent like parts of the invention.